just chiming in here to give people a heads up if they are on the 4.21 cfw and are going to downgrade and then upgrade to the new 4.30 cfw. well my upgrade to the 4.21 went so smoothly and the instructions for moving to the 4.30 should be just as smooth as long as I used the 4.25 to 3.55 downgrade pup to downgrade and then used QA toggle with rogeros 3.55 v2.7 piece of cake. NOT!!!
after the downgrade i spent an hour and a half stuck in limbo FW which i've labeled (LFW). now i verified that QA was enabled LIKE 50 TIMES but could not upgrade or downgrade. all attempts from the XMB either got me "use any firmware above 1.00 error " or it would get about 60 % through and then get corruption error.. any attempts from the recovery menu which by the way told me to use 4.40 or above (does not exist LOL) would either give straight corruption error or would load up only to tell me i'm all ready on the newest firmware.
i even tried factory service mode and only got RSOD for my troubles (gotta love that Lv2diag.self) i luckily have a couple of HDD's that are backed up with the higher and lower firmwares. put in kmew drive with 4.25 spoof on it and update to rogero's 355.v27 went in like there was never any problem at all form recovery.
if it wasn't for the backups i prob would of been sitting by the door waiting for a flasher. so i to believe there must be a break in the chain some where at the drive level. while in the (LFW) OS would lock randomly going across XMB icons. so back up before you upgrade and back up before you downgrade !!! and save them both